The invention relates to an improved connecting device for a push-barge system according to the preamble of the independent claim 1, with which connection device an engine driven vessel, a pusher, is connected to the pushed vessel, a barge.
A large number of pushers and push-barges as well as their connecting devices are known. The publication U.S. Pat. No. 20,944 presents a solution where the connection between the pusher and the barge can be adjusted to different levels according to whether the barge is loaded or not. U.S. Pat. No. 3,486,476 presents a connection apparatus which uses wires between the pusher and the barge as connection members. The vessels are also connected to each other with the aid of a side list and a groove. The publication U.S. Pat. No. 3,610,196 presents a connection manner between a pusher and a barge which uses hydraulically movable locking bars as connecting members. However, the connection height between the pusher and the barge is not selectable, which in many cases is considered to be a disadvantage. The publication U.S. Pat. No. 3,844,245 presents a connection apparatus for a pusher and a barge where the pusher has on its sides connection members to be pushed into grooves in the inner sides of the stern of the barge. Wedge-like connection members receive a good support from corresponding connection points, but the connection becomes very rigid, which can be a poor characteristic in some sea conditions. U.S. Pat. No. 5,055,323 presents a connection structure of a pusher and a barge, where a hydraulic cylinder pair mounted in the pusher moves a quite massive locking body, which is pushed into notches located in the barge. However, the apparatus has a very heavy structure and it is rather complicated, and applicable only for a fixed connection. The publication FI 103777 presents a connecting device of a push-barge system where the connection between the pusher and the barge is made with the aid of cylinder packages operated by a pressure medium, so that the end of the piston rod of the cylinder extends into a cup-like counterpart in the barge. If the used pressure medium is compressed air the connection is able to yield in rough sea, which can be considered an advantage. However, there is not presented any adjustment of the apparatus, which may be regarded as a disadvantage, because it should be possible to be able to adjust the flexibility of the connection in different sea conditions.
The object of the invention is to present an improved connecting device for a push-barge system which can be adjusted so that when the pusher and the barge approach each other, then the piston rod of the cylinder is able to move due to the forces between the vessels when said force exceeds a set level. In rough sea the motions of the pusher are then more even, and the crew will not experience the blows from the barge as unpleasant as when the connection is rigid. An object of the invention is also to utilise the pneumatic system of the pusher as the energy source, so thus no extra machinery is required.
The object of the invention is attained in the manner presented in the independent claim 1 and in the other claims. According to the invention the push-barge system uses an improved connecting device with which the engine driven vessel, a pusher, is connected to the pushed vessel, a barge. The connecting device includes a cylinder, which is fastened to the side of the pusher and which with its piston is operated by a pressure medium, and a counterpart, which is fastened to the barge and into which a connecting member connected to the piston is being supported due to the movement of the piston of the cylinder. The connecting device comprises a pressure restricting valve or the like through which the pressure medium can be discharged from said cylinder when, due to the effect of the mutually approaching movement between the barge and the pusher, said counterpart transmits to the piston via the connecting member a force, which is so high that the pressure caused by the piston will at least partially open the pressure restricting valve. Then the connection between the pusher and the barge can be made flexible, and then the movements of the pusher and the barge in rough sea will not be blow-like in the same way as in a rigid or almost rigid connection. As the crew of the pusher can adjust the operating limit of the pressure restricting valve it can be chosen so that it is more suitable, regarding the sea, the wind, the loading of the barge, the speed, as well as the characteristics and the size of the barge. The use of the device according to the invention will improve the working conditions of the crew in the pusher, and will also reduce the disadvantages caused to the vessel by a rough sea.
If said pressure restricting valve is adjustable, then the adjustment can be made any time and quite easily.
If the counterpart fastened to the barge is fastened to the board structure of the barge by welding or by bolted joints, then the fastening can be done for instance as a post-installation quite rapidly, and even then a sufficiently robust connection can be obtained.
If the connecting device receives its operating energy from the pneumatic system of the pusher, which provides compressed air with which the hydraulic oil of the connecting device is pressurised, then there is no need for a hydraulic machinery or a corresponding apparatus, as the pneumatic system of the pusher has a quite sufficient capacity for the energy supply to the connecting device according to the invention.
If there is an adjustable connecting device on both sides of the pusher, then the pusher can be adjusted regarding both sides, and regardless of the direction of the sea compared to the travelling direction.
If said pressurised medium is an almost non-compressible matter, such as hydraulic oil or the like, then the operation of the apparatus will experience no disadvantages caused by compression.
If the end of the piston rod is a cylindrical connecting member, or if such one is fastened to the end, which member can find suitable space to engage in the cylindrical notch of the counterpart, then the connecting joint will be simple and reliable at the same time.